Apparatus for advancing tunnel supports

ABSTRACT

Apparatus and method for continuously or intermittently advancing tunnel supports against surrounding earth pressure. Cutting edge and trailing shells are interconnected by a longitudinal frame or cage structure. Intermediate the forward and trailing shell are overlapping intermediate shells which are individually connected to the cage structure by hydraulic cylinders so that each intermediate shell can be moved longitudinally relative to the others and relative to the tunnel wall while the other intermediate shells engage the tunnel wall and advance the cage as well as the forward or support and trailing shells. The intermediate shells are sequentially moved forwardly, preferably by releasing the pressure exerted against the wall, as by contracting the shell or by projecting through the shell various-shaped devices which grip or penetrate the wall. The support may incorporate steering guidance means for adjusting the direction of the excavation device about perpendicular transverse aces. Means is also provided on the trailing shell for feeding out the rearward end ribbons, or rods to support the tunnel walls prior to concreting and also a retainer shell which functions as a screed for the concrete and supports the concrete as it is gaining strength.

Unite States Patent [1 1 Jacobs [54] APPARATUS FOR ADVANCING TUNNELSUPPORTS [76] Inventor: J. Donovan Jacobs, c/o Jacobs Associates, 500Sansome Street, San Francisco, Calif. 94111 [22] Filed: Apr. 2, 1971[21] Appl. No.: 130,686

Related U.S. Application Data [63] Continuation-in-part of Ser. No.798,097, Feb. 10,

[52] U.S. Cl ..61/84, 61/85 [51] Int. Cl ..E0lg 3/04 [58] Field ofSearch ..6l/84, 85, 42, 45, 61/63 [56] References Cited UNITED STATESPATENTS 3,169,376 2/1965 Cunningham ..61/84 X 3,382,002 5/1968 Tabor..61/85 X 1,355,290 10/1920 Updegraff .suss

3,487,649 1/1970 Bergstrom ..6l/85 3,379,024 4/1968 Wohlmeyer... ..6l/853,232,062 2/1966 Bland ..61/84 FOREIGN PATENTS OR APPLICATIONS 1,173,0346/1964 Germany ..6l/84 1,205,928 1*2/1965 Germany ..6l/85 PrimaryExaminerDennis L. Taylor Attorney-Julian Caplan [57] ABSTRACT Apparatusand method for continuously or intermittently advancing tunnel supportsagainst surrounding earth pressure. Cutting edge and trailing shells areinterconnected by a longitudinal frame or cage structure. Intermediatethe forward and trailing shell are overlapping intermediate shells whichare individually connected to the cage structure by hydraulic cylindersso that each intermediate shell can be moved longitudinally relative tothe others and relative to the tunnel wall while the other intermediateshells engage the tunnel wall and advance the cage as well as theforward or support and trailing shells. The intermediate shells aresequentially moved forwardly, preferably by releasing the pressureexerted against the wall, as by contracting the shell or by projectingthrough the shell various-shaped devices which grip or penetrate thewall. The support may incorporate steering guidance means for adjustingthe direction of the excavation device about perpendicular transverseaces. Means is also provided on the trailing shell for feeding out therearward end ribbons, or rods to support the tunnel walls prior toconcreting and also a retainer shell which functions as a screed for theconcrete and supports the concrete as it is gaining strength.

14 Claims, 20 Drawing Figures 5 Shoets$heet 1 INVENTOR. DONOVAN JACOBS AT T OR NEY Patented May 22, 1973 R mm @m m 3 m7 V i m mm Patented May22, 1973 5 Shuts-Sheet 2 FIG.4

, INVENTOR. J. DONOVAN JACOBS BY Q92 @2 4 ATTQRNEY Patented May 22, 19733 3,733,835

5 Shoots-Sheet 3 67c 31x 81c 670 INVENTOR. G 5 J. DONOVAN JACOBS BY Q 44 ATTORNEY Patented May 22, 1973 3,733,835

5 Shuts-Sheet 4 INVENTOR. J DONOVAN JACOBS ATTORNEY Patented May ZZ,1973 3,733,835

5 Shuts-Sheet 5 APPARATUS FOR ADVANCING TUNNEL SUPPORTS This applicationis a continuation-in-part of copending application Ser. No. 798,097filed Feb. 10, I969.

A tunnel excavation device may be of various types, one common typehaving a rotary cutting or boring head containing wheels or knives orblades which cut or scarify the rock or earth at the face of the tunnelcausing it to fall away from the face and thus creating the tunnel bore.Such device further incorporates means for picking up the material whichis loosened and discharging the material onto a conveyor forultimatedisposal. In order to operate effectively, the excavation device must beforced against the tunnel face with tremendous pressure and thisrequires an anchor or support for the device. Previously used supportsfor this purpose have certain disadvantages. A principal object of thepresent invention is the provision of improved means for anchoring thetunnel excavation device so that it may be forced against the face ofthe tunnel with the requisite pressure.

A further principal effect of the present invention is that the tunnelexcavation device is capable of advancing continuously, althoughintermittent advance is also possible. As a result, it is not necessaryto discontinue the excavating action while the support is being movedforwardly and thus the present invention reduces the time required forexcavation.

Another feature of the present invention is the fact that the supportmay be guided so that the excavation device will dig a curved path andthe direction of the curve and, within reasonable limits, the radius ofthe curve is subject to considerable variation under the control of theoperator.

Another principal feature of the present invention is the fact that themachine may operate in relatively soft ground where other tunnel boringhead advancing equipment will not adequately grip the tunnel wall orface. Thus, as hereinafter explained in detail, a plurality of shellsare brought into firm engagement with the tunnel wall immediately behindthe forward edge of the device and the combined effect of a plurality ofsuch shells engaging the wall adequately anchors the machine and enablesthe device to be forced forwardly with the necessary pressure. Inaddition, the movable shells adequately support the tunnel wall untilsuch time as concrete may be applied to the wall and provided sufficienttime to set or other structural support installed.

Accordingly, still another principal feature of the invention is thefact that the machine supports the tunnel wall rearwardly of theexcavation device against surrounding earth pressure for a sufficientdistance so that a concrete lining may be applied to the tunnel bore andallowed partially to set. Thus, the invention provides structure forsimultaneously advancing the excavating device and supporting in placethe earth and rock behind the head.

Still another feature of the invention is the fact that a plurality ofribbons, wires or rods are fed out adjacent the rear of the machine inclose proximity to the tunnel walls temporarily supporting the wallsuntil a more permanent structural support can be applied.

Another feature of the invention is the provision of a space to the rearof the support means providing access to the tunnel wall so thatconcrete under pressure may be used to face the wall surrounding theribbons, wires or rods which have heretofore been mentioned.

Still another feature of the invention is the provision of a trailingshell which follows the application of concrete and functions as ascreed and also supports the concrete for sufficient time to enable itto begin to set.

One of the features and advantages of the invention is the provision ofa concrete support which is moved continuously at the same speed atwhich the boring head advances in a continuous movement immediatelybehind the point of application of the concrete.

Other objects of the present invention will become apparent upon readingthe following specification and referring to the accompanying drawingsin which similar characters of reference represent corresponding partsin each of the several views.

In the drawings:

FIG. 1 is a vertical sectional view, partially broken away to revealinternal construction, of one form of machine in accordance with thepresent invention.

FIG. 2 is a transverse sectional view taken substantially along line 22of FIG. 1 in enlarged scale and partially broken away to conserve space.

FIG. 3 is a transverse sectional view taken substantially along line 3-3of FIG. 1.

FIG. 4 is a fragmentary view of the intermediate shell expanding meansas viewed substantially along line 4-4 of FIG. 2.

FIG. 5 is a fragmentary view of a hinge means for one of the steeringrings as viewed substantially along line 55 of FIG. 3.

FIG. 6 is a fragmentary sectional view in enlarged scale takensubstantially along line 66 of FIG. 3.

FIG. 7 is an enlarged fragmentary longitudinal sectional view through aportion of the rear of the machine.

FIG. 8 is a fragmentary longitudinal sectional view through a portion ofthe intermediate shells and surrounding structure.

FIG. 9 is a view similar to FIG. 8 of a modification.

FIG. 10 is a schematic view illustrating the method of the invention.

FIG. 1 l is a fragmentary sectional view of a modified gripping deviceshown in retracted position; FIG. 11A shows same in projected position.

FIGS. 12 and 12A are views similar to FIGS. 11 and 11A, respectively, ofa further modified device.

FIGS. 13 and 13A are views similar to FIGS. 11 and 11A of a stillfurther modified device; FIG. 13B is a plan of a portion of FIGS. 13 and13A.

FIGS. 14, 14A and 14B are views similar to FIGS. 13, 13A and 13B ofanother modified device.

The machine which is the subject of the present invention is installedas part of the equipment used to dig a tunnel having a face 21 which ishere shown vertical and a tunnel bore 22 which is here assumed to behorizontal and circular in cross-section. The face 21 is continuouslycut away usually by an excavating device (not shown) of a typecommercially available such as, for example, a boring head disposed withthe supporting structure 23 positioned immediately behind the face 21.As has heretofore been mentioned, the excavating device cuts orscarifies the tunnel face and the material displaced is collected andconveyed to the rear for disposal by means well understood in thetunneling art and not herein illustrated or described. Extendingrearward from the rear of the support 23 is a cage structure 24 or framewhich extends the entire length of the machine. Optionally, adjacent therear of the cage structure 24 a trailing support shell 26 may beconnected to the cage structure. It is a feature of the presentinvention that the support 23, cage structure 24 and trailing supportshell 26 move together and it is a further feature of the invention thatthe same are capable of advancing continuously at a substantiallyuniform rate, although in some installations they may moveintermittently. As an optional feature of the invention, the cagestructure 24 may extend rearwardly of the support shell 26 and beconnected to a concrete retainer shell 27 which is of a lesser diameterto provide for the facing of the tunnel wall with concrete 28, all ashereinafter explained.

The cage structure 24 is anchored by a plurality of intermediate shellrings, 29a to 29e shown in FIG. 1 as five in number, each overlappingthe adjacent rings and movable relative thereto and each articulatelyconnected to the cage structure 24 by a plurality of hydraulic rams 31ato 31c. In a preferred method of operation of the invention, all of theintermediate shells 29a to e but one is anchored to the tunnel wall 22and the rams 31 of the anchored shells are energized by hydraulicpressure to continuously force the cage structure 24 and accordingly thesupport structure 23 forwardly. The one shell 29 which is not anchoredto the tunnel wall moves forwardly to the limit of the stroke of its ram31, whereupon it is caused to be anchored to the tunnel bore 22 by meanshereinafter explained in detail, and thereupon the next rearwardintermediate shell 29 is disengaged from the tunnel wall and is movedforwardly until it abuts the shell which has preceded it. Each of theintermediate shells 29 is disengaged, advanced and re-engagedsequentially until the last of the intermediate shells 29e has beenmoved forwardly, whereupon the cycle is repeated with the forwardmostintermediate shell 29a being moved forwardly. Inasmuch as all but oneintermediate shell 29 is firmly engaged with the tunnel wall 21, aneffective means for anchoring the machine is provided which enables thecage structure 24 to be forced forwardly in the manner which has beendescribed. At the same time, inasmuch as the intermediate shell 29 isindividually sequentially being moved forwardly, the entire machinegradually advances, enabling the machine to move continuously ratherthan intermittently. Intermittent movement is contemplated as analternate, however. The parts of the machine will be described in order.

The excavating support 23 comprises annular rings which are the cuttingring 36 which is at the front and has a diameter equal to bore 22,smaller diameter horizontal steering ring 37, the vertical steering ring38 and the cage attachment ring 39. Ring 37 is within ring 36. Rings 38and 39 are enclosed within shell 41 which is of the same diameter ascutting ring 36. The horizontal steering ring 37 and vertical steeringring 38 are articulated. In the means of articulation here illustrated,at the top and the bottom of the machine is a vertically disposedsteering pin 42 and eyes 43, 44 fixed to rings 37, 38 and receiving pin42 in oversize holes to permit relative flexing of the rings, As shownin FIG. 6, the arrangement of eyes 43, 44 and pin 42 resembles anordinary door hinge. Disposed within horizontal steering ring 37 oneither side of the machine is a plurality of horizontal guidancecylinders 46, the rods 47 of which engage abutments 48 on the verticalsteering ring 38. When the cylinders 46 on the right-hand side of themachine are energized to project their rods 47 while those on theleft-hand side are energized to retract their rods, the horizontalsteering ring 37 tilts about the vertical axis of pins 42 to the left,thereby steering the cutting ring 36 to the left. If the oppositecylinders 46 are energized, then the machine is steered to the right. Ifboth sets of cylinders 46 are at neutral, the machine steers straightahead.

Between the vertical steering ring 38 and the cage anchor ring 39 oneither side of the machine are transverse horizontal steering pins 51which are received in eyes 52, 53 similar to eyes 43, 44 and affixed tothe rearward face of the vertical steering ring 38 and the forward faceof the cage support ring 39, respectively. Mounted in vertical supportring 38 is a plurality of vertical guidance cylinders 56, some at thetop and some at the bottom, the rods 57 of which engage abutments 58 onring 39. When the cylinders 56 at the top of the machine are energizedto project their rods 57 while the cylinders 56 at the bottom of themachine are energized to retract their rods 57, the machine tilts abouta transverse horizontal axis through the axes of pins 51 to steer thecutting head downwardly. When the energization of the cylinders 56 isreversed, the machine steers upwardly, and when the cylinders 56 at topand bottom are equally energized, the machine advances horizontally.

It will be seen that selective energization of the various guidancecylinders 46, 56 enables the machine to be steered to left or right orup or down, or that a compound curve may be generated. The guidancecylinders 46, 56 enable the machine to be steered in accordance with apredetermined path and also to compensate for any tendency of themachine to drift out of the desired path.

Connected to cage support ring 39 is the cage struc ture 24. Extendinglongitudinally of the machine is a plurality of horizontal struts 61equi-arcuately spaced around the perimeter of the cage structure. Aplurality of transverse vertical cage rings 62a to 62c are connected tostruts 61. The cage rings 62 are equi-distantly spaced longitudinally ofthe machine. The trailing support shell 26 is connected to the perimeterof the cage structure by brackets 63. Where a concrete retainer shell 27is used, the struts 61 extend further rearwardly and there is at leastone additional cage ring 62f and said shell 27 is connected to thestruts 61 by brackets 64. It will be seen that ring 39, struts 61,intermediate cage rings 62 and shell 26 (and, where used, shell 27) areinterconnected in a unitary structure.

In the form of the invention shown in FIGS. 2 and 4, each intermediateshell 29 is split along at least one longitudinal element 66 and isfurther formed with a plurality of inwardly projecting strengtheningribs 67. Shell 29 may be made to expand and contract and in expandedcondition the shell firmly engages tunnel wall 22 and movementlongitudinally relative thereto is impeded by the frictional engagementof the surface of the shell with the tunnel wall. When the shell iscontracted, the shell may be moved longitudinally relative to the tunnelwall. As has previously been mentioned, at any given instant, all of theintermediate shells 29 but one is expanded and in firm engagement withthe tunnel wall, whereas one shell is contracted and moves relative tothe wall to an advanced location. One means of expanding and contractingthe shells is illustrated in detail in FIG. 4. One or more cylinders 68is located bridging the split 66 in the shell perimeter, cylinder 68being pivotally connected by pin 69 to bracket 71 fixed to shell 29 onone side of split 66 and rod 72 of cylinder 68 is connected by pin 73 tobracket 74 on the other side of split 66. When cylinder 68 is energizedto extend rod 72, shell 29 is expanded and when cylinder 68 is energizedin the opposite direction to contract the rod 72, shell 29 iscontracted.

In the form of invention shown in FIG. 11, shells 29k do not expand andcontract in the manner illustrated in FIGS. 2 and 4. Apertures 111 areformed at spaced intervals around the shells and within the shellimmediately opposite such apertures are hydraulic cylinders 112supported by brackets 113. The rods 114 of cylinders 112 may be extendedthrough apertures 111 to penetrate or firmly engage tunnel wall 22kthereby anchoring the shell to the wall. As in the previousmodification, one shell of the series of shells is disengaged from thewall and this is accomplished by retracting rods 114 of that particularshell while all of the rods of the other shells are projected.

In FIG. 12 the ends 117 of rods 114 l are formed as conical points topenetrate the wall 22 1.

In FIG. 13 square or rectangular pads 118 are attached to the outer endsof rods 114m and apertures 111m are shaped to accommodate same. The pads118 when projected bear against the tunnel wall.

In FIG. 14 pads l18n are circular and formed with a plurality of points119. This form is particularly effective in rock or hard ground.

In other respects the structures of FIGS. 11-14 resemble the precedingmodification and the same reference numerals followed by subscripts k,l, m and n, respectively are used to designate corresponding elements.

As best shown in FIGS. 1 and 8, shells 29 are formed so that theyoverlap. Thus the exterior of leading edge 76a of the forwardmostintermediate shell 29a is relieved at its perimeter by somewhat morethan the thickness of the trailing edge of excavating support shell 41.At the trailing edge of the intermediate shell 29a the inner surface 77ais similarly internally relieved. Each of the intermediate shells 29b to29e is constructed similarly to the leading intermediate shell 290. Toaccommodate overlapping trailing support shell 26 and the last of theintermediate shells 29e the outer periphery 78 of the leading edge ofthe trailing support shell 26 is relieved. The individual shells 29 moveforwardly at any given time a distance which is slightly less than thelength of relief 76; hence at any instant the shells overlap.

Movement of the intermediate shells 29 is accomplished by energizationof a plurality of peripherally spaced propulsion cylinders 31a to 31e.The rearward end of each propulsion cylinder 31 is pinned by pin 81 tothe adjacent cage ring 62. The rod 82 of each such cylinder is pivotedby means of pin 83 to bracket 84 fixed adjacent the forward end of eachintermediate shell 29. Thus each cylinder 31 is fixed to cage structure24 and the position of each intermediate shell 29 relative to cagestructure 24 depends upon the position of its rod 82 relative tocylinder 31. Preferably, all of the cylinders associated with a givenintermediate ring 29 are energized equally and at the same time.Assuming that it is desired to advance the forwardmost of theintermediate shells 29a relative to the cage structure 24, it is assumedthat there is a gap in the overlap of said shell 29a relative to shell41 of structure 23 as is seen in FIG. 1 by exposure of relief 76a andshell 29a has been disengaged from the tunnel wall, the forwardmostcylinders 31a are energized to project their rods 82 and thus shell 29ais moved forwardly until the overlap is overcome. Thereupon shell 29a iscaused to engage the tunnel wall 22. Meanwhile the next rearward shell29b has been disengaged from the wall and each cylinder 31b is energizedto advance said shell 2% to overcome the gap which has been created inthe overlap between shells 29a and 29b. This sequential disengagementfrom the wall by shell 29, forward advance and re-engagement of the wallis continuously repeated from front shell 29a to rear shell 29e and thenrenewed at front shell 29a. However, the energization of the propulsioncylinders 31 to advance the individual intermediate shell relative tothe others is only part of the continuous cycle of energization of saidcylinders. Thus each cylinder 31 which is not immediately being used toadvance an intermediate shell 29 is continuously being energized toretract its rod 82 relative to the cylinder 31. Since rods 82 areconnected to the intermediate shells 29 which are in turn in firmengagement with the tunnel wall 22 and since the cylinders 31 areconnected to cage structure 24, the contraction of rods 82 continuouslyforwardly advances cage structure 24. Forward advance of cage structure24 pushes forwardly the support 23 for the excavating device and thusapplies a continuous pressure on the device.

The fit between the individual intermediate shells 29 is such that theymay twist relative to the longitudinal axis of the machine and relativeto each other sufficiently to follow the steering path of the steeringmechanism of the boring head support structure 23.

An annular gap is maintained between the underside of relieved portion77 at the trailing edge of each shell and the outer surface of eachleading edge 76. Thus when a preceding shell 29 is in contractedcondition its trailing edge does not impose pressure on the leading edgeof the succeeding shell which prevents the contracted shell from movingrelative to the expanded trailing shell.

Directing attention to FIG. 9, an alternate means for advancing themachine is disclosed. The intermediate rings 29x to 291 are articulatelyconnected to adjacent rings rather than to the cage structure. Thus therearward end of cylinder 31x is fixed by means of pin 81a to one of thereinforcing ribs 67a of intermediate rings 29y. Rod 82a is pivoted bymeans of pin 83a to one of the ribs 67a of the next forwardmostintermediate ring 29x. In other respects, the structure of FIG. 9, isessentially the same as that previously described and the same referencenumerals followed by subscript a are used to designate correspondingparts. However, in this structure, the advance of the boring headsupport 23 is intermittent rather than continuous. During such time asthe forwardmost intermediate ring 29 is being advanced, advance of theboring head support ring is discontinued. When such forwardmostintermediate ring is in forward position and engages the tunnel wall,the forward progress of the boring head support 23 is resumed.

FIG. 7 shows a preferred means for feeding a plurality of rearwardlyextending heavy wires 86, ribbons or small rods from the tail of thetrailing support shell 26. Thus a plurality of reels 87 of said wire,ribbons or rods is mounted by means of shaft 88 which are connected bybrackets 89 to struts 61. Suitable brakes (not shown) preventover-travel of the unwinding of reels 87 and maintain the wires 86 orrods taut at all times. Longitudinal slots 91 are formed in the trailingedge of shell 26 for the egress of wires 86 and said wires are held inplace near the periphery of the tunnel wall 22 by pulleys 92 mounted inbrackets 93 at the slots 91. Hence the wires 86 extend rearwardly andare spaced closely enough together so that they prevent large rocks anddebris falling into the tunnel behind the support ring 26. The termsupporting material is used herein to include not only reinforcing wire86 and rods but also ribbon, straps and flat sheets to perform a similarpurpose. The space between ring 26 and screed 27 is used to applyconcrete 28 to the tunnel wall and the wires support the wall 22 untilthe concrete 28 begins to set.

Screed 27 is of a diameter equal to the inside diameter of concrete 28and its periphery serves to smooth the concrete as it moves forwardly.Furthermore, screed 27 supports the concrete for a period of timesufficient to enable it to gain strength.

It will be understood that other permanent or semipermanent structuralsupports for the tunnel bore may be applied in addition to, or insteadof, concrete. For example, section metal shells may be inserted behindshell 29c or shell 26.

METHOD OF OPERATION Directing attention to FIG. 10, it will be observedthat only four intermediate rings 29g to 29j are shown in order toemphasize that the number is discretionary and also to simplifyexplanation of the method of operation. Steering devices and otherauxiliary features are eliminated for simplification. Cage 24 isrepresented by a single strut 101 having a cutting support member 3612at the front and a trailing shell 26 and four intermediate cylinderabutments 1023 to 102j. The cylinders 31g to 31] bear against abutments102g to 102j, while their rods 82g to j bear against brackets 84g to jon shells 29g to j respectively.

Vertical line 103 is a reference or datum line and does not representthe tunnel face except at the end of the completion of the cycle ofoperation illustrated. The cycle is shown in equal time intervalsproceeding from top to bottom of the figure, the initial position beingshown in sub-FIG. A and the last as sub-FIG. G; which is the same assub-FIG. A except that strut 101 has advanced from tunnel face 21A toreference line 103. The increment of movement of member 36b per timeinterval is indicated by numeral 104, and a feature of the invention isthe capability of advance continuously in equal increments per unit oftime.

In FIG. A the vertical arrows on members 29g-j indicate that these ringsbear against bore 22b. Gap 106 exists between 29g and 36b; gap 107between 29j and 261; (corresponding to shell 26 of FIG. 1). At thisinstant of time, none of the rings 29 is advancing. Note rod 82g isretracted, rod 82h projected one-fourth its travel, rod 821' one-half,and rod 82 three-fourths. Immediately after the instant of FIG. A, shell29g is disengaged from wall 22b as has been previously explained.

FIG. 108 shows no vertical arrows on shell 29g indicating it isdisengaged from the wall. The horizontal 10 j and shell 29g has advancedthe length of gap 106 toward reference line 103 by action of cylinder31g. Immediately after the instant illustrated in FIG. 10B, shell 29g iscaused to grip the wall and shell 29h to be disengaged.

FIG. 10 illustrates, therefore, the sequential gripping and release ofshells 29 relative to bore 22. It also illustrates gradual extension ofthe rods 82 connected to shells 29 which are gripping to therebygradually advance strut 101 and cutting ring 36b. Finally, itillustrates relatively rapid sequential advance of shells 29 which aredisengaged to eliminate the gap between said shells and the shell inadvance thereof. The fact that the rods 82 are projected differentdistances at each time interval is likewise illustrated.

During most of the cycle of movement each shell is in grippingengagement and the combined effect of the shells which engage the wallis to anchor strut 101 against the thrust of the cylinders 31 advancingring 36b. One shell 29, however, at almost every instant is disengagedand is moving forward relative to the others to close the gap ahead ofit. When such gap is closed, that shell is caused to engage the wall,and the next shell is disengaged and advanced.

Referring to FIGS. 1 9, if it is necessary to change the direction ofthe excavating device in order to bring it back into a straight line orto cause it to travel on a curve, the guidance cylinders 46 and 56 areused in a manner which has heretofore been explained, causing pivotalmovement of ring 37 relative to ring 38 about the axes of pins 42 and ofring 38 relative to ring 39 about the axes of pine 51. Because of thefact that there is not a tight engagement of ring 41 relative tointermediate rings 290, the two rings may twist slightly relative toeach other so that they follow the necessary curvature, and the samerelationship exists between the adjacent rings 29.

Where used, the wires 86 ribbons or rods are being continuously fed outthrough slots 91 at the trailing edge of the trailing support shell 26,lying in close proximity to the tunnel wall 22 and protecting theinterior of the tunnel from falling rocks and large lumps of dirt.Concrete 28 is applied as soon as the trailing support 26 has passed agiven point. Modern pneumatic concrete sets up rather rapidly so thatadvance of the tunnel boring machine and the setting up of the concreteis substantially simultaneous. Screed 27 is drawn over the interior ofconcrete 28 to smooth the same and it also provides additional supportwhile the concrete is gaining strength.

What is claimed is:

1. A machine for supporting earth around the periphery of a borecomprising a plurality of shells arranged end-to-end, each said shellmovable relative to adjacent shells in a longitudinal direction througha stroke of predetermined amplitude, means independently operable toadvance each said shell relative to the next shell through said stroke,whereby said machine advances relative to said bore, and gripping meansfor individually sequentially .causing each said shell to grip said boreto resist sliding movement of said shell relative to said bore in saidlongitudinal direction and then to release the-grip of said shell onsaid bore to permit sliding movement of said shell relative to said borein said longitudinal direction, each said shell being apertured in aplurality of locations and in which said gripping means comprises aplurality of hydraulic cylinders and mounting means mounting at leaseone said cylinder internally of said shell aligned with one of theapertures therein, said cylinders having rods adapted to project throughsaid apertures into gripping engagement with said bore to engage saidbore and restrain sliding movement of said shell relative to said borein said longitudinal direction.

2. A machine according to claim 1, which further comprises feet on theouter ends of said rods.

3. A machine according to claim 2 in which each said foot is asubstantially rectangular pad.

4'. A machine according to claim 3 in which each said foot is providedwith a plurality of points.

5 A machine according to claim 2 in which each said foot is pointed.

6. A machine according to claim 1, which further comprises a forwardsupport ahead of the forwardmost said shell, an articulated connectionmeans between said forward support and said forwardmost of said shells,said connection means having hinges pivoting about an axis transverse tothe direction of advance of said shells and guidance means for pivotingsaid support about said axis to guide the direction of advance of saidsupport relative to said shells.

7. A machine according to claim 6, in which said connection meanscomprises second hinges pivoting about a second axis transverse to saiddirection of advance and to the axis of said first-mentioned hinges andsecond guidance means for pivoting said support about said second axis.

8. A machine according to claim 1, which further comprises a screedconnected for movement with said shells in trailing relation to therearmost of said shells to provide a gap for concreting of said bore.

9. A machine according to claim 1, which further comprises supportingmaterial feed means and means adjacent the rear of said machine formounting said feed means to apply supporting material to said borerearward of said machine as said machine advances.

10. A machine for supporting earth around the periphery of a borecomprising a plurality of shells arranged end-to-end, means interposedbetween consecutive shells independently operable to advance each saidshell relative to the next shell, and a frame attached for movement withsaid shells inside said shells, said means comprising a plurality ofsets of activators, the number of said sets corresponding to the numberof said shells, said activators attached at one end to said frame and atthe other end to said shells.

11. A machine according to claim 10, in which said activators arehydraulic rams.

12. A machine according to claim 10, which further comprises a retainershell trailing said first-mentioned shells and fixed for movement withsaid frame, said first-mentioned shells movable relative to said frame,said retainer shell substantially non-movable relative to said frame.

13. A machine according to claim 12, whichfurther comprises a screedfixed to the rear of said frame with a gap between said retainer shelland said screed for concreting said bore.

14. A machine according to claim l3, which further comprises supportingmaterial feed means mounted on said frame to discharge supportingmaterial behind said retainer shell to the surface of said bore assaid'machine advances.

1. A machine for supporting earth around the periphery of a borecomprising a plurality of shells arranged end-to-end, each said shellmovable relative to adjacent shells in a longitudinal direction througha stroke of predetermined amplitude, means independently operable toadvance each said shell relative to the next shell through said stroke,whereby said machine advances relative to said bore, and gripping meansfor individually sequentially causing each said shell to grip said boreto resist sliding movement of said shell relative to said bore in saidlongitudinal direction and then to release the grip of said shell onsaid bore to permit sliding movement of said shell relative to said borein said longitudinal direction, each said shell being apertured in aplurality of locations and in which said gripping means comprises aplurality of hydraulic cylinders and mounting means mounting at leaseone said cylinder internally of said shell aligned with one of theapertures therein, said cylinders having rods adapted to project throughsaid apertures into gripping engagement with said bore to engage saidbore and restrain sliding movement of said shell relative to said borein said longitudinal direction.
 2. A machine according to claim 1, whichfurther comprises feet on the outer ends of said rods.
 3. A machineaccording to claim 2 in which each said foot is a substantiallyrectangular pad.
 4. A machine according to claim 3 in which each saidfoot is provided with a plurality of points.
 5. A machine according toclaim 2 in which each said foot is pointed.
 6. A machine according toclaim 1, which further comprises a forward support ahead of theforwardmost said shell, an articulated connection means between saidforward support and said forwardmost of said shells, said connectionmeans having hinges pivoting about an axis transverse to the directionof advance of said shells and guidance means for pivoting said supportabout said axis to guide the direction of advance of said supportrelative to said shells.
 7. A machine according to claim 6, in whichsaid connection means comprises second hinges pivoting about a secondaxis tRansverse to said direction of advance and to the axis of saidfirst-mentioned hinges and second guidance means for pivoting saidsupport about said second axis.
 8. A machine according to claim 1, whichfurther comprises a screed connected for movement with said shells intrailing relation to the rearmost of said shells to provide a gap forconcreting of said bore.
 9. A machine according to claim 1, whichfurther comprises supporting material feed means and means adjacent therear of said machine for mounting said feed means to apply supportingmaterial to said bore rearward of said machine as said machine advances.10. A machine for supporting earth around the periphery of a borecomprising a plurality of shells arranged end-to-end, means interposedbetween consecutive shells independently operable to advance each saidshell relative to the next shell, and a frame attached for movement withsaid shells inside said shells, said means comprising a plurality ofsets of activators, the number of said sets corresponding to the numberof said shells, said activators attached at one end to said frame and atthe other end to said shells.
 11. A machine according to claim 10, inwhich said activators are hydraulic rams.
 12. A machine according toclaim 10, which further comprises a retainer shell trailing saidfirst-mentioned shells and fixed for movement with said frame, saidfirst-mentioned shells movable relative to said frame, said retainershell substantially non-movable relative to said frame.
 13. A machineaccording to claim 12, which further comprises a screed fixed to therear of said frame with a gap between said retainer shell and saidscreed for concreting said bore.
 14. A machine according to claim 13,which further comprises supporting material feed means mounted on saidframe to discharge supporting material behind said retainer shell to thesurface of said bore as said machine advances.